The invention is based on a tube mounting. Such tube mountings are used in particular in wiper systems for motor vehicles.
There, they are secured by a wiper carrier, known as a tube mounting, to the body of a motor vehicle. The mounting includes a motor mounting, which carries a wiper drive mechanism with a wiper motor and a gear mounted on it. A power takeoff shaft of the gear is supported in a gear dome and, as a rule via a crank and connecting rods, it drives cranks that are solidly connected to a drive shaft for each wiper. The gear housing is as a rule screwed with three screws to the motor mounting, which is held by a mounting tube. The screws, which are distributed about the gear dome and are inserted through screw holes in the motor mounting, engage existing screw supports of a housing cap on the power takeoff side. The screw supports brace the gear housing on the motor mounting.
The drive shaft of the wiper is supported in a wiper bearing, whose bearing housing is secured to or formed onto the ends of the mounting. The mounting is secured directly to a vehicle body via the bearing housing or via fastening eyelets that are formed onto the bearing housing, the mounting, and/or the motor mounting.
From German Utility Model DE-GM 74 34 119, a tube mounting is known that is made from a square tube to which a plate acting as the motor mounting is welded. Such tube mountings or tubular frame systems are highly stable despite their lightweight construction. For cost reasons, the goal is a straight carrier tube, because then no preliminary bending work is needed.
From European Patent Disclosure EP 04 09 944 B1, a tube mounting is also known in which a motor mounting connects tubular parts via positive connections. A variant shows that the motor mounting can be embodied integrally with a housing cap of the gear housing.
European Patent Disclosure EP 0 781 691 A1 shows a tube mounting with a motor mounting and a mounting tube. On the side toward the mounting tube, the motor mounting has an indentation in which the mounting tube is embedded and is joined, the one located over the other, by means of projection welding. The cross-sectional contour of the indentation corresponds to the cross-sectional contour of the mounting tube and surrounds the mounting tube over a circumferential range of approximately 180. Since the motor mounting is thus joined to the mounting tube over only a few points on only one side of the mounting tube, the forces occurring in wiper operation are unfavorably distributed to the connection between the two components, so that locally high material stresses occur. Furthermore, because of the spacing between the mounting tube and the power takeoff shaft, considerable bending moments arise.
From European Patent Disclosure EP 0 689 975 A1, a tube mounting with a motor mounting is also known. It comprises two parts embodied in mirror symmetry, which on the side toward a mounting tube have indentations in which the mounting tube is embedded. The indentations each surround the mounting tube over a circumferential range of approximately 180, so that the two indentations together surround the mounting tube over its entire circumference. Upon assembly, both parts of the motor mounting are placed around the mounting tube and joined together, for instance mechanically or by adhesive bonding or by a thermal connection. The mounting tube is fixed relative to the motor mounting circumferentially and axially positively and/or materially by adhesive bonding. The two parts of the motor mounting can also, in one embodiment, be combined into a single piece. Once again, the spacing between the power takeoff shaft and the mounting tube is considerable.
The tube mounting has the advantage that the mounting tube is enclosed on both sides, and the incident forces are distributed not only via the indentation but also via the tab to the surface of the motor mounting. This is possible because the indentation does not extend along the edge of the motor mounting but rather traverses it. As a result, the latch can be cut out inside the motor mounting and can aid in distributing the force of flow to multiple sides of the indentation.
According to the invention, the motor mounting is a shaped sheet-metal part. The indentation preferably extends between at least one screw hole and the opening for the gear dome. As a result, the mounting tube is located near the power takeoff shaft of the gear, so that only slight bending moments occur. Adjacent to the opening for the gear dome and transversely to the indentation, a tab is cut out, which is curved contrary to the indentation and encloses the mounting tube. As a result, the mounting tube is retained over virtually its entire circumference. The forces that arise in wiper operation are thus distributed in the region of the gear dome over a large circumferential region of the mounting tube, and purely bending stresses are partly converted into tensile and compressive stresses. Despite the favorable induction of force, the motor mounting has a simple design and comprises a single piece, which has no undercuts or double-walled regions and can be made as a part shaped by bending.
The motor mounting and the tab in alternation surround the mounting tube from opposite sides, and the individual regions are relatively narrow in comparison to the total connection region. As a result, they can be joined to the mounting tube simply and in controlled fashion positively by adhesive bonding or welding, for instance projection welding.
To increase the strength, it is expedient to reinforce the material connection with a positive connection, for instance by giving the mounting tube and the corresponding indentation in the motor mounting and/or the tab a cross section other than a circular cross section. To increase the strength, slits whose ends are rounded are also provided laterally of the tab. As a result, the notch stress is reduced, and stress and fatigue cracks in these regions are avoided.